System and method for displaying anatomy and devices on a movable display

ABSTRACT

An image display system is provided comprised of a virtual window system that creates a visual coherency between the patient&#39;s anatomical images and the actual patient by aligning the image on the display to the patient and then presenting the image to the user in a way that feels as if the user is looking directly into the patient through the display. The image shown within the image display system is dependent upon the position of the image display apparatus and the position of the user so that the display orientation of the image may be biased slightly toward the user to improve ergonomics and usability.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit as a continuation of U.S.application Ser. No. 14/286,793, filed May 23, 2014, entitled “Systemand Method for Displaying Anatomy and Devices on a Movable Display,”which claims the benefit of U.S. Provisional Application No. 61/829,078,filed May 30, 2013, entitled “System and Method for Displaying Anatomyand Devices on a Movable Display,” which is hereby incorporated byreference in its entirety.

BACKGROUND 1. Field of the Invention

The invention relates generally to the diagnosis and treatment ofdisorders using minimally invasive techniques. In many minimallyinvasive procedures very small devices are manipulated within thepatient's body under visualization from a live imaging source likeultrasound, fluoroscopy, or endoscopy. Live imaging in a minimallyinvasive procedure may be supplemented or replaced by displaying theposition of a sensored medical device within a stored image of thepatient anatomy.

Many minimally invasive procedures are conducted in expensive settingsby specialized physicians. Often small, percutaneous medical devices arevisualized during the procedure by using live fluoroscopic or ultrasonicimaging. While the live imaging provides a real-time image of anatomy,it has many drawbacks:

Time spent in an imaging suite is expensive and raises the cost of manyminimally invasive medical procedures.

Ionizing radiation used to create the fluoroscopic image is dangerous tothe patient, physician, and assistants.

Needles, Guidewires, and other small devices may be difficult to locatewithin the live two-dimensional image. These devices may be too small tosee clearly in fluoroscopic images. In ultrasound images, these devicesmay be difficult to locate when they are outside of the ultrasonicimaging plane or they may reflect a diffused, ambiguous image when theyare within the ultrasonic imaging plane.

The fluoroscopic and ultrasonic images are two-dimensional and do notprovide determinant information about motion of the medical device andthree-dimensional anatomical structures.

During a typical minimally invasive procedure the physician must lookaway from the patient and his or her hands to see the display showingthe live image. Additionally, the frame of reference for the live imageis typically misaligned from the frames of reference for the physician,the tool and the patient. This presents a challenging situation for thephysician who must compensate for differences in these frames ofreference. For instance, when the physician inserts a device into thepatient by moving his hands from left to right, the fluoroscopic imageof the device moves towards the top of the display. Ultrasonic imagescan be even more confounding in that the frame of reference for theultrasound image is based on the position and orientation of theultrasound probe which is frequently moving during imaging. Thephysician must compensate for the misalignment of the coordinate systemsfor the respective frames of reference while also concentrating onachieving the goals of the minimally invasive procedure. The physician'sneed to look away from the patient and his or her instrument creates anergonomic challenge in addition to this mental challenge. As a resultthe completion of minimally invasive procedures becomes delayed,increasing the procedure cost.

Prior to a minimally invasive catheter procedure, patients often have ananatomical image created using CT or MR imaging systems commerciallyprovided by companies like Philips, Siemens, General Electric, andToshiba. The anatomical images can be processed, or “segmented,” intothree-dimensional representations of the anatomy of interest. Individualorgans, muscles and vasculature can be visually separated from otheranatomy for even clearer viewing of regions of interest. In thisinvention the three-dimensional pre-procedure images may be used insteadof or in addition to live imaging for navigation during the procedurebecause the position and orientation of the medical device can be sensedin real-time. For example, navigation systems provided by Medtronic. GE,and Stryker sense the positions of medical devices within the patient'sbody and present the sensed position data in a pre-procedural image ofthe patient's anatomy. These navigation systems provide a supplement orreplacement to fluoroscopic imaging so that the physician may conduct aminimally invasive procedure within the patient's body using little orno X-ray. However, the navigation systems do not provide a means formaking the physician's hand motions on the medical device match themotions of the device displayed in the image of the anatomy on thedisplay. In order to make minimally invasive procedures easy andintuitive, the coordinate systems of the patient, the device, thedisplay, and the physician's hands must be unified.

Minimally invasive procedures w % here a medical device is inserted intothe body are especially well suited for a system that providesnavigation assistance by unifying the physician, patient, display, anddevice coordinate systems. These procedures usually employ devices thatare navigated through the body to small anatomical targets. For example,to obtain a tissue biopsy of a prostate, a physician may insert a smallcatheter through the urethra into the bladder. The urethral catheterprovides an ideal location for the placement of sensors that can be usedby software to match the live three-dimensional shape of the urethra tothe stored three-dimensional shape of the urethra in the pre-operativeimage set. This “registration” of the real-time position of thepatient's soft tissue to the pre-operative image of the same tissueallows the tissue and adjacent tissue structures to be accessed usingthe pre-operative images. Then a biopsy needle may be inserted intobiopsy targets within the prostate by a physician who is navigating theneedle using a three-dimensional image of the prostate. Once targettissue is reached with a needle, it may be treated directly withtherapies like RF ablation, cryo-therapy, brachy-therapy orchemo-embolozation. Similar use of the invention may be made for othertissues like breast, liver, lung

Endoscopic device use may similarly be improved by displaying ananatomical image that is aligned to the patient. Prior to inserting theendoscope, it is difficult to know the exact locations of anatomicalstructures within the body. After the endoscope is inserted, theexternal references of the patient's body are lost. Displaying ananatomical image that is aligned to the patient's body provides contextby unifying the external view of the patient with the internal view ofthe anatomy, allowing the physician to choose optimal placement ofaccess ports and improving the ability access desired anatomy quicklyand directly.

Robotic surgical procedures may be improved to displaying the projectedworkspaces of robotic devices on an anatomical image that is aligned tothe patient. The projected path, workspace, and collision space ofrobotic devices may be overlaid on the anatomical image and viewed fromdifferent perspectives by moving the display, allowing the user tooptimize the placement of the devices in the patients body for reachingspecific target anatomies.

The present invention improves the ease and reliability of visualizinganatomy within a patient by providing a system for displaying the deviceand patient anatomy in a substantially aligned manner.

2. Description of Background Art

Relevant references include US2010/295931; US2010/05315; US2010/039506;US2009/322671; U.S. Pat. Nos. 7,880,739; 7,203,277; 5,808,665;7,774,044; 5,134,390; 6,038,467; and Nikou C, DiGioia A M, Blackwell M.,et al. Augmented reality imaging technology for orthopaedic surgery.Operative Techniques in Orthopaedics. 2000; 10:82-86.

SUMMARY

The invention comprises a virtual window system that creates a visualcoherency between the patient's anatomical images and the actual patientby aligning the image on the display to the patient and then presentingthe image to the user in a way that feels as if the user is lookingdirectly into the patient through the display. The invention is designedto also display medical devices, such as a biopsy needle. The inventionmakes the anatomy and the motion of the minimally invasive medicaldevice in the display match the motion of the physician's hands bysubstantially unifying the coordinate systems of the patient, themedical device, the display, and the physician's hands. The inventioncreates a visual coherency between the motion of the medical device inthe image and the motion of the physician's hands manipulating thedevice. This invention also creates a visual coherency between themotion of the image in the display and the motion of the display. Forexample, the invention shows the image of the anatomy, the projectedpath of the biopsy needle, and the actual location of the tip of thebiopsy needle in a single image that is shown on a display over thepatient in substantial alignment to the patient's actual anatomy.

Embodiments of the invention possess inventive design elements thatprovide excellent user ergonomics and increase the functional anatomicalworkspace of the virtual window surgical system. Coupling the positionand orientation of the display to the image allows the image to remainaligned to the patient for various positions and orientations of thedisplay. To improve the ergonomics and workspace of the system, theknowledge of the general position of the user relative to the patient isleveraged to slightly bias the image position to an optimized position.For example, if the user is on the left side of the patient, the imagemay be angled fifteen degrees away from the user so that when thedisplay is angle fifteen degrees toward the user, the image will appearflat relative to the patient. Practice has shown that the intuitivebenefits to the user of an aligned image may still be captured whensmall angular offsets are in place, with offsets of 30 degrees being thewell-tolerated limit in many procedures. The system uses the knowledgeof the user's position to bias the display toward more comfortablepositions. The knowledge of the user's position may be input to thesystem by the user, inferred by the system using the position of thedisplay, or sensed by the system using position or contact devices onthe system. To further increase the workspace of the system, thisinvention allows for decoupling the relationship to reposition thedisplay independently of the image. For instance, an aligned display mayinterfere with other equipment during some portion of the procedure andit may be desirable to reposition the display slightly to relieve theinterference. Additionally this invention allows for a scaled couplingfor improved ergonomics. For instance, moving the display with a unityratio may cause the display to interfere with other equipment duringsome portion of the procedure or may make the screen difficult to view.Up to a 1.5:1 scale may be used to optimize the ergonomics of the systemwhile maintaining the visual coherency between the patient and theimage. It should be noted that the display may be repositioned alongmultiple axes and in multiple directions and that the scaling may bedifferent for different axes and directions. For example, the scalingmay be unity in the translational axes and 1.3:1 in the rotational axes.

Additionally this invention provides a movable support structure to holda display directly in front of the physician, between the physician andthe patient. Ideally the images are presented in a fashion such that theimages are substantially aligned with the patient. This inventiondetails the methods and techniques needed to align the images to thepatient. Many embodiments utilize a display that is mounted on a movablesupport structure that allows for the display to be positioned betweenthe patient and the physician. The range of motion of the supportstructure and the degrees of freedom enable a wide range of displaypositions and orientations. In one embodiment, the patient is lying onan exam table with the physician standing by the patient's side. Thesupport structure allows the display to be brought over the patient. Thephysician can move and orient the display so the display is locatedroughly between the physician and the patient. Providing a display overthe operative area of the patient allows the physician to performminimally invasive procedures with needles, Guidewires, and catheters asif the physician were performing open surgery by looking directly intothe patient.

Techniques are also disclosed to track the position of the display, theimaging source, the patient, and the medical device. Tracking individualelements of the system allows the image to be aligned with the patientand constantly updated to accommodate for a moving patient, movingmedical device, or moving display.

A live image of the patient anatomy may also be shown on a displaylocated over the patient. Sensors track the position and orientation ofthe display screen and the imaging source so that the position andorientation of the display screen may control position and orientationof the imaging source, keeping the anatomical image, the medical deviceimage, and the patient substantially co-aligned. Alternatively, sensorstrack the position and orientation of the display screen and the imagingsource so that the position and orientation of the imaging source maycontrol position and orientation of the display screen, to keep theanatomical image, the display screen, the medical device image, and thepatient substantially co-aligned. The live image may be supplementedwith other anatomical images from live or static sources that aresensored, registered, and displayed in the same substantially co-alignedmanner on the display screen. For example, a live endoscopic image maybe superimposed over a three-dimensional image of the prostate derivedfrom a pre-operative MR scan. As the physician moves the display to viewthe three-dimensional image from different angles, the endoscope may beremotely automatically re-positioned so that the live image viewingposition matches the viewing position of the three-dimensional image.

All embodiments create a coupling between the image position andorientation and the position and orientation of a secondary systemcomponent. This invention improves the workspace of the system byproviding an input device to temporarily decouple the relationship toreposition the display or secondary system component for improvedworkspace. Additionally, this invention improves the ergonomics byallowing for a scaling factor between the coupled display and secondarysystem component.

In another embodiment the system comprises a processor further adaptedto receive image data for the patient's anatomy. Such image data may bea static image obtained by M RI, ultrasound. X-ray, computed tomographyor fluoroscopic imaging modalities. The image data can also be a livefluoroscopic image collected in real-time. The system can further trackpatient position by one or more of the following: fiducial markers, liveimaging data, optical sensors, or electromagnetic sensors. The processoris also further adapted to receive position data from a tool, which istracked by electromagnetic sensors. The display is held by a support armhaving at least one degree of freedom, wherein the members and joints ofthe support arm may be operatively coupled to counterbalance springs orweights. The processor is further adapted to receive position data ofthe display, which is tracked by one or more of the following: opticaltracking, electromagnetic sensors, or encoded joints of the support arm.The processor processes the various position data and image data todisplay an image of the patient's anatomy substantially aligned with thepatient's actual anatomy superimposed with the position of any devicebeing tracked. The processor is also adapted to direct any live imagingequipment to ensure proper functioning of the system. When used in asurgical setting the invention may be located in the surgical field andmay also comprise a sterile drape for the display to protect theintegrity of the surgical field.

In one embodiment, a live image of the patient anatomy is shown on arepositionable display screen located over the patient. The physiciancan move the display over the patient while sensors track the motion ofthe display so that the image shown on the display screen may beperiodically or constantly updated to show the medical device, and thepatient anatomy substantially aligned with the patient from theperspective of the user with a slight angular bias toward the user. Theposition of the user relative to the patient may be entered by the userat the start of the procedure by touching a button on the displaylabeled “patient left,” “patient right,” “patient head,” or “patientfeet.” In this manner, the image shown on the display provides a view ofthe medical device and patient anatomy that is intuitive, ergonomic, andallows for easy navigation of the medical device within the patientanatomy shown on the display screen. While the image of the anatomy isfrequently based on a pre-operative image, a live image may besupplemented with other anatomical images from live or static sourceswhich are sensored, registered, and displayed in the same substantiallyco-aligned manner on the display screen.

In additional embodiments, a sensor on the medical device providesposition and orientation data of the device to a data processor. Asensor on the patient provides position and orientation data of thepatient to the processor, and sensors on the display screen provide theviewing position and orientation of the display screen to the processor.With data from the medical device, the patient, and the display, theprocessor unifies the three coordinate systems so that the image shownon the display screen substantially matches the position of the patientanatomy. Adjustments to the display position over the patient result insimilar changes to the position of the image in the display: changingthe position of the display changes the view of the image on the displayscreen. For example, the user may change the angle of the display tochange the angle of the apparent image on the display screen or maytranslate the display to pan the image in the display along the patientto show different anatomy. Aligning the positions of the shown image andthe patient anatomy helps coordinate the physician's control of themedical device.

Elements of both embodiments may be combined to display preoperative andintra-operative anatomical images within the same procedure. In bothembodiments, the invention provides a virtual window into the patientwhere the physician may view the anatomy and navigate the surgicaldevice in substantial alignment with the patient. For example, sensoredendoscope may be show relative to the aligned anatomical image. Ananatomical target may be chosen and marked on the image. As sensoredmedical devices are moved to different potential access points on thebody, the ability to reach the anatomical target may be shown byprojecting the path of the device to the target and presenting apositive indication when the path to the anatomical target isuninterrupted. Similar real-time updates may be used to assist inquickly choosing access points for minimally invasive devices by showingwhether adjacent medical devices will collide with each other, externalanatomy, or internal anatomy as different potential access points on thebody are selected by moving the medical device to those access points.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe claims. A better understanding of the features and advantages of thepresent invention will be obtained by reference to the followingdetailed description that sets forth illustrative embodiments, in whichthe principles of the invention are utilized, and the accompanyingdrawings of which:

FIG. 1 is a side diagrammatic view of a system for displaying asubstantially co-aligned anatomical image with a sensored medical deviceover a patient's anatomy.

FIG. 2 is a block diagram showing data flow for the system in FIG. 1.

FIG. 3 is an isometric view of an embodiment of the display and supportarm positioned next to the patient table with the projected workspace ofa robotic surgical device overlaid on the anatomy in the display.

FIG. 4 is an isometric view of an embodiment of the display and supportarm positioned next to the patient table.

FIG. 5 is a flow chart describing the basic steps for a minimallyinvasive procedure using a sensored medical device and the system fordisplaying a co-aligned image.

DETAILED DESCRIPTION

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. It is intended thatthe following claims define the scope of the invention and that methodsand structures within the scope of these claims and their equivalents becovered thereby.

FIGS. 1-2 describe an embodiment for navigating a minimally invasivemedical device within the patient using an acquired three-dimensionalanatomical image shown in a display 7 that is substantially aligned tothe patient anatomy. A sterile cover may be used to separate the displayfrom the sterile operating field and the sterile cover may incorporate aconductive film to provide a sterile touch interface for a capacitivetouch screen display. The sterile display cover may be a flexible, cleardrape made of plastic like polyethylene or polyurethane film, a rigidplate made of clear plastic like polycarbonate or acrylic, or acombination of both flexible and rigid plastics. The display ispreferably a light-weight, flat LCD display provided by manufacturerslike LG Display, Philips, and Innolux or a light-weight, flat OLEDdisplay provided by manufacturers like Samsung and Sony. A prime exampleof such a display would be the NEC TFT color LCD module which provides ausable viewing angle of 85° in all directions. In FIG. 1, the positionof the medical device within the patient 5 is provided by anelectromagnetic coil sensor located on the distal elongated section ofthe medical device 1. The position of the sensor is derived through anelectromagnetic transmitter 2 similar to those transmitters suppliedcommercially by NDI and Ascension Technology Corporation. Alternatively,the position of the medical device may be derived from an optical fiberposition sensor like that supplied by Luna Innovations. A similarpatient reference sensor 3 is placed on the patient in a reliably stableposition like the outcropping of the pelvic bone, sternum or clavicle.The reference sensor or sensors provide frequently updated datadescribing the position of the patient anatomy in the same coordinatesystem as the medical device sensor. The patch holding the patientsensor may be placed on the patient before the patient's anatomy ofinterest is imaged and the patch may contain known X-ray visiblematerials such as tungsten, platinum-iridium, platinum, barium sulfideor iodine and MR visible materials such as gadolinium or vitamin E. Thepatch is visible within the image of the anatomy and therefore thepatient reference sensor 3 can be registered to the three dimensionalanatomical image. Position data from the sensor in the medical device 1and patient reference sensor 3 and display support arm 4 are sent to thesystem processor 6. The local coordinate systems of the medical devicesensor 1 and display 7 may undergo a coordinate system transformation inthe system processor so that the positions of the device sensor, patientsensor, and display may be evaluated in a single world coordinatesystem. Display 7 has a user input button 8. FIG. 2 shows the flow ofsensor position data from the sensor buffer 9 to the system processor 10where the position sensor data is used by the processor to place an iconof the medical device into the three-dimensional patient anatomy imagefor display through the system display 11. The system processor is astandard computing system like those supplied by Dell or Hewlett Packardrunning an operating system like Windows or Linux. Position data fromthe system display and support arm is likewise used by the systemprocessor to orient the image on the screen so that the image, based ondisplay position data from the display 7 and support arm 4 and patientposition data from the patient reference sensor 3, is substantiallyaligned with the patient anatomy. Display position data may also be usedto modify the image in the display, for example zooming or clipping theimage as the display moves closer to the patient. Other imagemodifications may include changing transparency, removing layers,removing anatomical structures, or changing colors. Additionally,scaling of the image in discrete steps or image modifications may bedone via a touch sensitive surface on the display.

FIG. 3 shows a movable display 12 positioned over a surgical tableshowing an image of the patient anatomy. A target 13 may be chosen onthe image of the anatomy. A remote electromagnetic transmitter, such asthose commercially available from Northern Digital Incorporated (NDI)and Ascension Technology Corporation, is positioned near or under thetable to localize sensors 15 on at least one medical device 16. As thedisplay is moved, the image of the anatomy, the medical devices,projected the path 14 of the medical devices, and the collisionboundaries of the medical devices is repositioned to provide the optimumview for navigation of the medical device within the anatomical image.The access points may be chosen to optimize the ability of the medicaldevices to reach the anatomical target without creating collisions ofthe medical devices that are internal and external to the patient and tooptimize the ability of the medical devices to reach the target anatomywithout intersecting other anatomical structures. Software may beemployed to present the collision-free projected path to the anatomicaltarget in an intuitively obvious manner by, for example, showing freepath as a green line and a path with collisions as a red line.

FIG. 4 presents an embodiment of the display and support arm withcounterbalanced joints at the support arm elbow 18, and shoulder 19. Anadditional rotational or linear joint is provided at the base of theshoulder 20 to allow the display to move along the inferior to superioraxis of the patient. All support arm joints may be encoded to providedata describing the position of the display. The display support isshown in an embodiment where the arm is mounted to a portable cart thatis positioned next to the patient table. Axis 17 allows the display torotate. An alternate embodiment may attach to the table or imagingsystem.

FIG. 5 provides an overview of the procedure flow for a minimallyinvasive procedure using a stored image for navigation. The patientanatomy is scanned 21 with a non-invasive imaging modality like CT, MRor rotational angiography. The imaged anatomy is stored and segmentedinto a three dimensional image, and borders and centerlines ofanatomical structures are calculated using commercially availablesoftware from vendors like Philips, Siemens, GE, Toshiba. TerraRecon,Calgary Scientific, Materialise, or Osirix. The image is transferred tothe memory of the system processor and the image is registered 22 to thesystem coordinate system along with the patient and the medical devicesensors. Registration of the image may be done by imaging the patientwith an image-visible skin patch, by touching a sensored probe toprominent bony anatomical points, or with an externally anatomicalmarker placed on the patient. At least three separate points of thepatch are visible in the image and then a position sensor is placed intothe patch. The visible points on the patch or bones may be selected onthe displayed image and then the known distance from the marker is usedto register the image to the patient position sensor. The patientposition sensor and medical device position sensor are inherentlyregistered because their positions are determined by the same sensingsystem. Next, the registered image is shown 23 above the patient in amanner substantially aligned to the patient anatomy. The image positionmay be biased slightly toward the user to provide improved ergonomics.For example, if the user is on the right side of the patient, the usermay press a button on the display touch screen to inform the system ofthe user's operating position. The system processor will then bias theimage rotationally by a small amount, usually 15-30 degrees, toward theuser. The system may also bias rotational scaling in the user'sdirection, creating a rotation scale factor that increases slightly asthe display is moved rotationally away from the user. In this way, theimage is biased toward ergonomically comfortable viewing positions forthe user without losing the substantial alignment of the image to thepatient that provides for improved perception and usability. The medicaldevice may be navigated 24 within or near the patient as the positionsensor in the medical device is tracked and presented as an image iconwithin the image of the patient anatomy. The image of the anatomy andthe image of the medical device may be shown with varying degrees oftransparency to maximize the visibility of the device and anatomicalimages. The display, showing the image of the medical device within theimage of the anatomy, may be repositioned 25 to enhance the viewingangle of the anatomy. As the display is moved, the image on the screenis updated to maintain substantial alignment between the displayedanatomical image and the patient anatomy.

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 29. Amedical system for displaying a tool in patient anatomy, comprising: arepositionable display coupled to a support arm including at least onerotational joint, wherein the repositionable display is mounted on aportable cart and configured to show a first image and a second image ofa patient simultaneously, the first image comprising a live endoscopicimage of the patient and the second image comprising an image derivedfrom a pre-operative scan of the patient; a tool insertable into thepatient, the tool comprising a sensor for providing position sensor dataof the tool to a data processor, wherein the position sensor data isused by the data processor to place an icon of the tool into the imagederived from the pre-operative scan; and a robotic device configured tocontrol movement of the tool to an anatomical target within the patient,wherein the data processor is configured to mark the anatomical targeton the image derived from the pre-operative scan and present acollision-free projected path to the anatomical target that is overlaidon the image derived from the pre-operative scan on the repositionabledisplay.
 30. The medical system of claim 29, wherein the support armcomprises counterbalanced joints at a support arm elbow.
 31. The medicalsystem of claim 29, wherein the second image of the patient is derivedfrom a computed tomography scan.
 32. The medical system of claim 29,wherein the second image of the patient includes a live fluoroscopicimage of the patient.
 33. The medical system of claim 29, wherein thesecond image of the patient is a three-dimensional image segmented froma computed tomography scan.
 34. The medical system of claim 29, whereinthe tool comprises a catheter.
 35. The medical system of claim 34,wherein the catheter comprises a urethral catheter.
 36. The medicalsystem of claim 29, wherein the tool comprises an endoscope.
 37. Themedical system of claim 29, wherein the tool comprises a biopsy needle.38. The medical system of claim 29, wherein the sensor of the toolcomprises an electromagnetic sensor.
 39. The medical system of claim 29,wherein the sensor comprises a fiber optic sensor.
 40. The medicalsystem of claim 29, wherein the data processor provides a positiveindication when the collision-free projected path is uninterrupted asthe tool moves through patient anatomy.
 41. The medical system of claim29, wherein the data processor further presents collision boundaries ofthe tool within the patient anatomy.
 42. A medical system for displayinga tool in patient anatomy comprising: a repositionable displayconfigured to show a first image and a second image of a patientsimultaneously, the first image comprising an intraoperative image ofthe patient and the second image comprising an image derived from apre-operative scan of the patient; a tool insertable into the patient,the tool comprising a sensor for providing position sensor data of thetool to a data processor, wherein the position sensor data is used bythe data processor to place an icon of the tool into the image derivedfrom the pre-operative scan; and a robotic device configured to controlmovement of the tool to an anatomical target within the patient, whereinthe data processor is configured to mark the anatomical target on theimage derived from the pre-operative scan and present a collision-freeprojected path to the anatomical target that is overlaid on the imagederived from the pre-operative scan on the repositionable display. 43.The medical system of claim 42, wherein the repositionable display iscoupled to a support arm.
 44. The medical system of claim 43, whereinthe support arm comprises an elbow with a rotational joint.
 45. Themedical system of claim 43, wherein the support arm is mounted on aportable cart.
 46. The medical system of claim 42, wherein the secondimage of the patient is derived from a computed tomography scan.
 47. Themedical system of claim 42, wherein the sensor of the tool comprises anelectromagnetic sensor.
 48. The medical system of claim 42, wherein thesensor comprises a fiber optic sensor.
 49. The medical system of claim42, wherein the tool comprises a biopsy needle.
 50. The medical systemof claim 42, wherein the data processor provides a positive indicationwhen the collision-free projected path is uninterrupted as the toolmoves through patient anatomy.
 51. The medical system of claim 42,wherein the data processor further presents collision boundaries of thetool within the patient anatomy.